If I add the same setting in following 3 config files: 1. Web.config of system 2. Machine.config of system 3. Web.config at root level What would be the order of application of that particular setting

In ASP.NET, configuration hierarchy applies settings from most specific to most general: root Web.config (3) → application-specific Web.config (1) → Machine.config (2). The root Web.config overrides application Web.config, which overrides Machine.config. This allows specific settings to take precedence over broader system-wide defaults.